The compressive strength of samples containing fly ash with high content of calcium sulfate and calcium oxide

2001 ◽  
Vol 31 (7) ◽  
pp. 1101-1107 ◽  
Author(s):  
T. Sebök ◽  
J. Šimonı́k ◽  
K. Kulı́sek
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Calcium Sulfate

Autoclaved Brick from Semi-Dry Desulfuration Ash

2011 ◽  
Vol 217-218 ◽  
pp. 846-851 ◽  
Author(s):  
Hao Li ◽  
Feng Qing Zhao ◽  
Qian Li ◽  
Lin Lin Fu ◽  
Shao Jie Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Natural Resources ◽  
Calcium Oxide ◽  
Calcium Sulfate ◽  
Solid Wastes ◽  
Solid Ratio ◽  
Autoclave Curing ◽  
Calcium Sulfite

The modified desulfurized ash is prepared through autoclave curing the desulfurized ash for 6 h at 175.4 oC in the presence of 2.0 wt% Fe2O3 and 0.75 wt% H2O2. In this process, 47.64 % of the calcium sulfite in the desulfurized ash is converted into calcium sulfate. The autoclaved brick is made by 36 wt% modified desulfurized ash, 24 wt% fly ash, 32 wt% sand and 8 wt% stones. The water-solid ratio is 0.10. The compressive strength of the brick is up to 15.7 MPa. For this method, the calcium oxide and calcium sulfate in the modification desulfurized ash are used to replace the lime, gypsum and other materials. The solid wastes are reused and natural resources are saved.

scholarly journals Gene-Expression Programming-Based Model for Estimating the Compressive Strength of Cement-Fly Ash Stabilized Soil and Parametric Study

2021 ◽  
Vol 6 (12) ◽  
pp. 181
Author(s):  
Van-Ngoc Pham ◽  
Erwin Oh ◽  
Dominic E. L. Ong
Keyword(s):  
Gene Expression ◽  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Parametric Study ◽  
Soil Stabilization ◽  
Gene Expression Programming ◽  
Superior Performance ◽  
Stabilized Soil ◽  
Research Findings

The study aims to develop a reliable model using gene-expression programming (GEP) technique for estimating the unconfined compressive strength (UCS) of soil stabilization by cement and fly ash. The model considered the effects of several parameters, including the fly ash characteristics such as calcium oxide (CaO) content, CaO/SiO2 ratio, and loss of ignition. The research results show that the proposed model demonstrates superior performance with a high correlation coefficient (R > 0.955) and low errors. Therefore, the model could be confidently applied in practice for a variety of fly ash qualities. Besides, the parametric study was conducted to examine the effect of fly ash characteristics on the strength of soil stabilization. The study indicates that if the fly ash contains a high amount of calcium oxide, the strength of fly ash stabilized soil is significant. In addition, fly ash could be used in combination with cement to increase the strength of the mixture. A fly ash replacement ratio is suggested from 0.19 to 0.35, corresponding to the total binder used from 10% to 30%. The research findings could help engineers in optimizing the fly ash proportion and estimating the UCS of soil stabilization by cement and fly ash.

Effects of Activators on Compressive Strength of Fly Ash-Based Geopolymers

2011 ◽  
Vol 197-198 ◽  
pp. 830-836
Author(s):  
Dong Min Wang ◽  
Pei Fu Cheng ◽  
Fan Fan ◽  
Yun Fen Hou ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Water Glass ◽  
Solution Concentration ◽  
Solid Content ◽  
Strength Development ◽  
Obvious Effect ◽  
Compressive Strength Development ◽  
Visible Effect

The effects of different activators on compressive strength of fly ash-based geopolymers have been studied. It is discovered that, alkali solution doesn’t have obvious effect, while Na2SiO3 solution has visible effect, the strength of samples rise with the increase of Na2SiO3 solution concentration. The effect of K2SiO3 solution is more obvious than Na2SiO3 solution, the strength of samples tend to first increase and then decrease with the increase of K2SiO3 solution concentration. The K2SiO3 solution with concentration of 2 M is the best activator to prepare geopolymers, which has compressive strength of 28.8 MPa at 28 d. When water glass are used as activators, the best modulus and solid content for Na-water glass (Na2O•nSiO2) are 1.2 and 32%, respectively. On this condition the sample’s compressive strength at 28 d is 38.9 MPa. However crystal calcium oxide is harmful for the compressive strength development, which is different with the conclusion accepted abroad.

Compressive Strength and Setting Time Modification of Class C Fly Ash-Based Geopolymer Partially Replaced with Kaolin and Metakaolin

2018 ◽  
Vol 766 ◽  
pp. 157-163 ◽  
Author(s):  
Khanthima Hemra ◽  
Shuntaro Yamaguchi ◽  
Takaomi Kobayashi ◽  
Pavadee Aungkavattana ◽  
Sirithan Jiemsirilers
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Setting Time ◽  
Xrd Analysis ◽  
Raw Material ◽  
Initial Setting Time ◽  
High Calcium ◽  
Initial Setting ◽  
Class C

Class C fly ash is widely used as a geopolymer raw material. It contains high calcium oxide and iron oxide resulting in a fast setting property. The influence of using kaolin and metakaolin replaced class C fly ash in geopolymer processing were investigated in term of compressive strength and setting time. Kaolin and metakaolin which calcined at different temperature of 600°C and 700°C replaced Class C fly ash between 0 to 50 wt. %. The geopolymers were prepared at constant KOH concentration as 6.0 M, K2SiO3/KOH ratio as 1.0, solid/liquid ratio as 1.5 and 7 days of curing. The compressive strength is obviously increased when fly ash was replaced with both kinds of metakaolin, although, it is inclined to decrease when replaced by kaolin. The compressive strength is increased up to 13% and 47% with the replacement by 50 wt. % of metakaolin calcined at 600°C and 700°C, respectively. On the other hand, the replacement by 50 wt. % of kaolin give the initial setting time prolonging from about 6 min to 80 min. However, the initial setting time of metakaolin calcined at 600°C and 700°C replacement is also improved to about 37 min and 20 min, respectively. These results from their difference of amorphous phase and reactivity of the replacement materials. XRD analysis reveals the combination phases of amorphous geopolymer gel that is the broad hump centered at 28 – 30° 2θ, and products from the reaction such as calcium oxide, arcanite, calcium silicate hydrate, quartz and muscovite which the two latter are from unreacted metakaolin. They are confirmed by FT-IT result and microstructure evaluation by SEM. Therefore, the partially replacement of fly ash with kaolin and metakaolin in fly ash-based geopolymer production are affected to the compressive strength and resulted to modify the setting time.

COMPRESSIVE STRENGTH AND THERMAL CONDUCTIVITY OF WATER AND AIR CURED PORTLAND CEMENT-FLY ASH-SILICA FUME MORTARS

2018 ◽  
Vol 17 (9) ◽  
pp. 2023-2030
Author(s):  
Arnon Chaipanich ◽  
Chalermphan Narattha ◽  
Watcharapong Wongkeo ◽  
Pailyn Thongsanitgarn
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume

COMPRESSIVE STRENGTH ANALYSIS ON PROBLEMATIC SOILS STABILIZED WITH FLY ASH IN JORDAN

2018 ◽  
Vol 17 (8) ◽  
pp. 1855-1861
Author(s):  
Nicolae Taranu ◽  
Monther Abdelhadi ◽  
Ancuta Rotaru ◽  
Maria Gavrilescu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Analysis ◽  
Problematic Soils

The Effect of Dry Mix Sodium Hydroxide onto Workability and Compressive Strength of Geopolymer Paste

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
A. Z. Mohd Ali ◽  
◽  
N. A. Jalaluddin ◽  
N. Zulkiflee ◽  
◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
High Emission ◽  
New Material ◽  
Curing Regime ◽  
Solid Form ◽  
Geopolymer Paste

The production of ordinary Portland cement (OPC) consumes considerable amount of natural resources, energy and at the same time contribute in high emission of CO2 to the atmosphere. A new material replacing cement as binder called geopolymer is alkali-activated concrete which are made from fly ash, sodium silicate and sodium hydroxide (NaOH). The alkaline solution mixed with fly ash producing alternative binder to OPC binder in concrete named geopolymer paste. In the process, NaOH was fully dissolved in water and cooled to room temperature. This study aims to eliminate this process by using NaOH in solid form together with fly ash before sodium silicate liquid and water poured into the mixture. The amount of NaOH solids were based on 10M concentration. The workability test is in accordance to ASTM C230. Fifty cubic mm of the geopolymer paste were prepared which consists of fly ash to alkaline solution ratio of 1: 0.5 and the curing regime of 80℃ for 24 hours with 100% humidity were implemented. From laboratory test, the workability of dry method geopolymer paste were decreased. The compressive strength of the dry mix of NaOH showed 55% and the workability has dropped to 58.4%, it showed strength reduction compared to the wet mix method.

scholarly journals Mechanical Behavior of Brick Masonry in an Acidic Atmospheric Environment

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2694 ◽  
Author(s):  
Shansuo Zheng ◽  
Lihua Niu ◽  
Pei Pei ◽  
Jinqi Dong
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Acid Rain ◽  
Cement Mortar ◽  
Brick Masonry ◽  
Atmospheric Environment ◽  
Peak Strain ◽  
Lime Mortar ◽  
Attenuation Model

In order to evaluate the deterioration regularity for the mechanical properties of brick masonry due to acid rain corrosion, a series of mechanical property tests for mortars, bricks, shear prisms, and compressive prisms after acid rain corrosion were conducted. The apparent morphology and the compressive strength of the masonry materials (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), the shear behavior of the masonry, and the compression behavior of the masonry were analyzed. The resistance of acid rain corrosion for the cement-lime mortar prisms was the worst, and the incorporation of fly ash into the cement mortar did not improve the acid rain corrosion resistance. The effect of the acid rain corrosion damage on the mechanical properties for the brick was significant. With an increasing number of acid rain corrosion cycles, the compressive strength of the mortar prisms, and the shear and compressive strengths of the brick masonry first increased and then decreased. The peak stress first increased and then decreased whereas the peak strain gradually increased. The slope of the stress-strain curve for the compression prisms gradually decreased. Furthermore, a mathematical degradation model for the compressive strength of the masonry material (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), as well as the shear strength attenuation model and the compressive strength attenuation model of brick masonry after acid rain corrosion were proposed.

Investigation on a New Hydraulic Cementitious Binder Made from Phosphogypsum

2013 ◽  
Vol 864-867 ◽  
pp. 1923-1928
Author(s):  
Yue Xu ◽  
Jian Xi Li ◽  
Li Li Kan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Active Carbon ◽  
High Strength ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Cementitious Material ◽  
Saturation Ratio ◽  
Tricalcium Aluminate ◽  
Cementitious Binder

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

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